Following the first confirmed case of West Nile Virus in the Okanagan this week the Resort Municipality of Whistler is reviewing its management plan, which could include using pesticides to target mosquitoes in the larval stage, or even adult mosquitos if the risk is high enough.
Heather Beresford, manager of environmental stewardship for the municipality, says she has already contacted Vancouver Coastal Health to determine if the response rating for the virus has moved up from Tier 1 - monitoring - to Tier 2, which could require some form of mitigation and public education.
"When a virus is identified in a community you step up your response and we have a plan of action when the virus is first identified," she said. "That would mean undertaking the application of a larvacide within areas where a type of mosquito is known to be located. From past monitoring we know where the higher risk areas are, the areas that are favoured by the types of mosquitoes that spread the virus."
If the virus appears, the municipality may use a different type of pesticide to kill adult mosquitoes as well. Both biological pesticides are included in the recent municipal bylaw that would limit the type of pesticides used in Whistler.
So far the virus has not cropped up in the Lower Mainland or Sea to Sky region, but given the rapid spread of West Nile throughout North America it will likely only be a matter of time. A monitoring project has been testing mosquito larvae collected from Whistler ponds and swamps since 2004 but did not include 2009.
"This just happens to be the year where the UBCM (Union of B.C. Municipalities) cut funding for monitoring in Whistler, which is also the year that we're seeing our first cases in the Okanagan," said Beresford. "Instead the UBCM put that funding into monitoring in a handful of high risk areas, and I'm sure that the Kootenays and the Okanagan were among them because of their proximity to Washington State."
Beresford expects to see monitoring return to Whistler next year now that the virus has reached British Columbia.
If anything the virus is overdue. By 2005 the virus was confirmed across the border in Alberta and to the south in Oregon, Idaho and Washington, and was expected to turn up in B.C. Only Alaska and the Canadian territories have not turned up cases at this point.
The virus is transferred between aggressive Class 3-plus types of mosquito that can feed off both birds and mammals, which are found almost everywhere in North America and around the world.
Most cases of West Nile virus in humans are relatively minor, with symptoms similar to the flu. In some cases it can lead to meningitis or encephalitis and result in death, although fatalities are rare. Since 2006 there have been just two West Nile deaths in Canada, although there were 14 deaths in 2003 and 18 in 2002 - before most communities had monitoring and action plans in place.
There is a higher fatality rate among lifestock and especially birds.
Beresford will make a presentation to council on West Nile this fall, reviewing the current management plans and information from Vancouver Coastal Health.